Iron in mined salt blocks?

[KarenM]

Hi Julianne,

No doubt Dr Tucker will weigh in with his expertise, but in the meantime… Do you mean those reddish blocks sold at feed stores? Those aren’t good in part because of the binders in them. I’d avoid them. Somewhere in the materials on this site Dr Tucker talks about salt and mineral blocks.

It’s my understanding that a horse would have to ingest a lot of iron before there’s a problem. Perhaps there is potential for issues depending on the geographic region and depending on what else is fed? I know there are trimmers who follow a certain trend that have jumped on the “iron is bad bandwagon” without understanding the whole picture. Iron is in everything naturally. It’s my understanding that extra iron is not usually added (don’t quote me) but the amount in the product would be the key to that. Trimmers are right to focus on good nutrition for hoof health, but I would verify nutrition information from those who have extensive study in that area.

[JulianneR]

Hi KarenM — thank you so much for your response! At our current barn, the horses have access to a plain, white salt block, because the barn owner believes that mineral salts have too much iron (hence the reason for my post). If I understand correctly, the recommended salt block is the Redmond or Himalayan, not the reddish ones from the feed store. Interested to see what Doc T says, but my feeling is he will agree with what you wrote 🙂

[Doc-t]

Thanks @JulianneR and @KarenM – here is a long answer.

The hoof is mostly protein and with chronic protein deficiency, I would think the farriers, trimmers and veterinarians would be focusing on amino acid replacement rather than discuss minerals where there is no outward evidence of a mineral deficiency. The concern about minerals has come from hair analysis showing a “deficiency” in certain minerals. Yet hair is also protein and so also suffers from a chronic protein deficiency.

As a reminder, there is a protein deficiency caused from 1) no broad spectrum amino acid source in the mono-grass pastures and hay and 2) gluconeogenesis from feeding excess glucose (grains, hay with pasture, treats). These have been thoroughly discussed in other blogs, forums and in the nutrition course.

I am not seeing a vitamin or mineral deficient horse with the exception of starvation cases. Iron makes up at least a third of the earth and it is everywhere. However all minerals require a ligand to be absorbed across the gut wall via the chelation process. This is how minerals are regulated within our bodies. Most iron is used as heme as in hemoglobin – the molecule that carries oxygen through the blood. Bleeding causes a loss of total body iron but any excess iron is either never absorbed or, if injected (as in an “iron shot”) is sequestered in the fat.

It is true that excess of certain minerals in the gut can prevent the absorption of other minerals. See my blogs about the reason grain manufacturers add dicalcium phosphate in all grain feeds. Excess phosphorus from grain blocks the absorption of calcium but the excess calcium blocks magnesium. However grain was an addition made by man in recent years. Iron has been around since the beginning of time and is ubiquitous. The horse has adapted to this.

How does the mineral content affect the hooves in light of the protein argument?They are most likely used in enzymes. But the observations from so many here indicate that adding high quality protein and removing all minerals other than water and a mined salt lick improves the hooves in about 2 to 4 months with continuing improvement for 12 to 24 months.

I am sure that the biology is very complex. To me, the obvious concern is lack of protein and not a mineral imbalance. If anyone has some evidence where with the addition (or subtraction) of minerals profoundly changes the health of the hooves and hair, I would love to see it.

[JulianneR]

Thanks for weighing in, Doc T. So my bottom line is: feed high-quality protein + forage and a mined mineral salt block!